Method for enhancing resistance gene removal and promoting humification in aerobic compost

Abstract

A method for enhancing resistance gene removal and promoting humification in an aerobic compost, which method comprises mixing livestock and poultry manure with compost auxiliary materials, adjusting the water content, adding an MnFe2O4 additive, and then performing aerobic composting for 20-30 days. Compared with conventional composting methods, the mature compost product obtained by means of the method exhibits a 60%-73% reduction in the relative abundance of sulfonamide resistance genes, a 50%-57% reduction in tetracycline resistance genes, a 20%-80% reduction in macrolide resistance genes, and a 45%-66% reduction in aminoglycoside resistance genes, and shows approximately a 15% increase in humic acid HA. This method achieves both efficient harmless treatment and resource utilization of organic solid waste.

Description

A method for removing resistance genes and promoting humification in enhanced aerobic composting Technical Field

[0001] The invention belongs to the field of solid waste treatment, and in particular relates to a method for removing resistance genes and promoting humification in enhanced aerobic composting. Background Art

[0002] The overuse and even misuse of antibiotics has accelerated the emergence of drug-resistant bacteria. Approximately 700,000 people die annually worldwide from antibiotic-resistant bacteria, a number projected to reach 10 million by 2050, resulting in economic losses of up to $100 trillion. Microbial resistance has become one of the world's most serious public health challenges. The United Nations Environment Programme has listed antibiotic resistance genes (ARGs) as the first of six emerging environmental issues. Livestock and poultry farming is a significant source of antibiotic resistance, and livestock and poultry manure is a significant reservoir of ARGs. When applied as fertilizer to farmland soil, it significantly increases the variety and abundance of ARGs in the soil. Studies have found that the abundance of 63 ARGs subtypes in soils treated with manure is 192 to 28,000 times higher than in control soils (Zhu YG, Johnson TA, Su JQ et al., Diverse and abundant antibiotic resistance genes in Chinese swine farms. Proceedings of the National Academy of Sciences of the United States of America, 2013, 110(9): 3435-3440.). ARGs in soil can further enter crops through the "soil-plant" system and ultimately pose a potential threat to human health through the food chain. Therefore, effectively preventing the spread of ARGs in livestock and poultry manure in the environment has become a social public safety need.

[0003] Aerobic composting is one of the most important ways to decontaminate, reduce and recycle livestock and poultry manure. However, traditional aerobic composting processes have problems such as slow biotransformation, incomplete decontamination, and low humification (low fertilizer efficiency). Existing studies have shown that although antibiotics can be degraded during composting, the resistance genes induced by antibiotics cannot be effectively reduced after traditional aerobic composting (Su JQ, Wei B, Qu Y et al., Antibiotic resistome and its association with bacterial communities during sewage sludge composting. Environmental Science & Technology, 2015, 49(12): 7356-7363.). The application of additives is the main technical strategy for enhancing composting. At present, composting additives mainly include microbial agents and biochar and other material additives. Chinese patent CN116948883A discloses a composite Bacillus bioagent for reducing sulfonamide resistance genes sul1, sul2 and integron gene intI1 in aerobic composting of pig manure. Chinese patent CN116730755A discloses a method for promoting the degradation of lignocellulose in lignocellulose organic waste compost by inoculating it with efficient lignocellulose hydrolyzing bacteria, thereby improving the quality of the compost product. However, microbial agents generally have high requirements for composting conditions, and exogenous microorganisms often cannot compete with indigenous microorganisms, so the effect is often not obvious in actual production. Chinese patent CN107129374A discloses a method for using bamboo biochar to reduce the abundance of tetracycline resistance genes in organic fertilizers. The method involves high-temperature cracking of bamboo at 600°C to produce biochar, which is then added to the compost at 2.5% of the dry weight of the compost material. The abundance of three tetracycline resistance genes in the biochar-treated compost was significantly lower than that in the control group. Chinese patent CN 115196616 A discloses a method for reducing ARGs in manure by using magnesium salt-modified biochar material. The method comprises mixing rice husk biochar with a magnesium salt solution to prepare a magnesium salt-modified biochar material, and adding the material to the compost material at 2% of the weight of the manure. Overall, the absolute abundance of sulfonamide resistance genes (sul2, dfrA1, dfrA7), macrolide resistance genes (ermF, ermB), and MGEs integron gene (intI1) in the magnesium salt-modified biochar addition group was lower than that in the control group, while the absolute abundance of sul1, sul2, dfrA7, and ermF genes in the ordinary biochar treatment group was significantly higher than that in the control group. The paper "Spectroscopic Characterization of Humus in Compost Added with Different Proportions of Corn Biochar" (Hou Zhibin, Xie Yiping, Cao Changchun, Xu Jintao. Science, Technology and Engineering, 2023, 23(26): 11459-11475.) disclosed that adding 10% and 15% corn biochar to compost can increase the humus content of the product.It can be seen that the biochar materials in these reported schemes usually use a large amount (2%-20% of the dry weight of the material), which greatly increases the production cost and is not conducive to field promotion and application.

[0004] MnFe2O4 is a type of spinel ferrite catalyst. Its microstructure, including variable oxygen vacancies and easily excited energy bands in the lattice, leads to variable microinterface properties. Currently, there are no reports on the application of MnFe2O4 in aerobic composting to reduce resistance genes and enhance humification. Summary of the Invention

[0005] In order to solve the technical problems of incomplete harmlessness and low humification degree in existing aerobic composting methods, the present invention provides a method for utilizing MnFe2O4 to enhance the removal of resistance genes and promote humification in aerobic composting.

[0006] Specifically, the present invention is achieved through the following technical solutions:

[0007] 1) Raw material preparation:

[0008] Mix livestock and poultry manure and compost auxiliary materials, adjust the moisture content to 55%-65% (preferably 60%), and the carbon-nitrogen ratio to 20-30 (preferably 25 C / N), and add MnFe2O4 additive along with water to obtain compost raw materials;

[0009] The livestock and poultry manure includes one or more of pig manure, chicken manure, sheep manure or cow manure;

[0010] The composting auxiliary material is one or more of wheat straw, corn straw, rice straw or sawdust, which are crushed to a length of less than 3 cm;

[0011] The fresh weight ratio of livestock and poultry manure and compost auxiliary materials is 3:1-6:1;

[0012] The added amount of the MnFe2O4 additive is 0.01%-0.5% of the dry weight of the initial compost material.

[0013] 2) Aerobic composting:

[0014] Conventional aerobic composting is performed using the prepared compost raw materials. The compost is turned every 2-3 days during the temperature rise and high temperature periods, and every 7 days during the temperature drop and mature period. The high temperature period (above 50°C) of the compost is not less than 5 days, and the aerobic composting time is 20-30 days. This can enhance the removal of resistance genes in the compost product and promote humification. The compost product meets the organic fertilizer maturity standard (NY / T525-2021).

[0015] The aerobic composting method in this step is a conventional composting method in the art, such as the method disclosed in the literature (Sun HJ, Chen S, Zhu N et al., Hydrothermal carbonization aqueous phase promotes nutrient retention and humic substance formation during aerobic composting of chicken manure. Bioresource Technology, 2023, 385: 129418.).

[0016] In one embodiment of the present application, the additive MnFe2O4 used in the above technical solution is prepared by the following hydrothermal method: 0.1 mol L -1 Ferric chloride and 0.05 mol L -1 Mixed solution of manganese chloride, add 3 mol L -1 The suspension was then injected into an autoclave, which was then placed in a muffle furnace and heated to 250°C at a rate of 10°C / min for 12 hours. After the reaction was complete and the autoclave cooled to room temperature, the sample was removed and washed several times with alternating deionized water and ethanol until the pH of the eluate remained stable. Finally, the sample was dried in a vacuum drying oven at 60°C for 12-24 hours, ground, and passed through a 300-mesh sieve to obtain a dark brown powder, which was the MnFe2O4 additive.

[0017] In this application, the terms "antibiotic resistance gene" and "resistance gene" refer to resistance genes for sulfonamides, tetracyclines, macrolides, and aminoglycosides. The term "enhancing or promoting humification" refers to increasing the humic acid content and improving the fertilizer efficiency of compost products.

[0018] Compared with existing aerobic composting methods, the method for removing resistance genes and promoting humification in enhanced aerobic composting provided by the embodiments of the present invention has the following beneficial effects:

[0019] 1) The enhanced removal of resistance genes and the humification effect in the embodiment are significant. At the end of the composting in the embodiment, the relative abundance of sulfonamide resistance genes in the obtained compost product is reduced by 60%-73% compared with the control (wherein the relative abundance of sul1 gene is reduced by 60%-73% compared with the control, and the relative abundance of sul2 gene is reduced by 24%-69% compared with the control); the relative abundance of tetracycline resistance genes is reduced by 50%-57% compared with the control (wherein the relative abundance of tetC gene is reduced by 60%-84% compared with the control, the relative abundance of tetG gene is reduced by 25%-41% compared with the control, the relative abundance of tetM gene is reduced by 42%-53% compared with the control, the relative abundance of tetO gene is reduced by 12%-88% compared with the control, and the relative abundance of tetW gene is reduced by 10%-20% compared with the control). Compared with the control, the relative abundance of tetX genes decreased by 42%-64%, and the relative abundance of macrolide resistance genes decreased by 20%-80% (among which the relative abundance of ermB gene decreased by 26%-57%, the relative abundance of ermC gene decreased by 1.4%-65%, and the relative abundance of ermF gene decreased by 11%-99%). The relative abundance of aminoglycoside resistance genes decreased by 45%-66% (among which the relative abundance of aadA gene decreased by 46%-77%, and the relative abundance of aadD decreased by 14%-43%). Humic substance HS increased by 2%-14% and humic acid HA increased by 6%-15% compared with the control.

[0020] 2) The method is simple to operate, has low material costs, and is pollution-free. The MnFe2O4 structure is highly controllable, and its interfacial properties can be manipulated by adjusting the metal molar ratio, calcination temperature, and time. This allows for targeted adaptation to the polyphenol-Maillard reaction catalytic mechanism, while achieving efficient, harmless, and resourceful treatment of organic solid waste, making it suitable for large-scale deployment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1a is a comparison of the relative abundance changes of sulfonamide resistance genes in the 0.01% MnFe2O4 addition group and the control group during the composting process of Example 1;

[0022] Figure 1b is a comparison of the relative abundance changes of tetracycline resistance genes in the 0.01% MnFe2O4 addition group and the control group during the composting process of Example 1;

[0023] Figure 1c is a comparison of the relative abundance changes of macrolide resistance genes in the 0.01% MnFe2O4 addition group and the control group during the composting process of Example 1;

[0024] Figure 1d is a comparison of the relative abundance changes of aminoglycoside resistance genes in the 0.01% MnFe2O4 addition group and the control group during the composting process of Example 1;

[0025] FIG2 is a comparison of the changes in humic substance HS and humic acid HA content in the 0.01% MnFe2O4 addition group and the control group during the composting process of Example 1;

[0026] Figure 3a is a comparison of the relative abundance changes of sulfonamide resistance genes in the 0.1% MnFe2O4 addition group and the control group during the composting process of Example 2;

[0027] FIG3b is a comparison of the relative abundance changes of tetracycline resistance genes in the 0.1% MnFe2O4 addition group and the control group during the composting process of Example 2;

[0028] Figure 3c is a comparison of the relative abundance changes of macrolide resistance genes in the 0.1% MnFe2O4 addition group and the control group during the composting process of Example 2;

[0029] Figure 3d is a comparison of the relative abundance changes of aminoglycoside resistance genes in the 0.1% MnFe2O4 addition group and the control group during the composting process of Example 2;

[0030] FIG4 is a comparison of the changes in humic substance HS and humic acid HA content in the 0.1% MnFe2O4 addition group and the control group during the composting process of Example 2;

[0031] Figure 5a is a comparison of the relative abundance changes of sulfonamide resistance genes in the 0.5% MnFe2O4 addition group and the control group during the composting process of Example 3;

[0032] FIG5b is a comparison of the relative abundance changes of tetracycline resistance genes in the 0.5% MnFe2O4 addition group and the control group during the composting process of Example 3;

[0033] Figure 5c is a comparison of the relative abundance changes of macrolide resistance genes in the 0.5% MnFe2O4 addition group and the control group during the composting process of Example 3;

[0034] Figure 5d is a comparison of the relative abundance changes of aminoglycoside resistance genes in the 0.5% MnFe2O4 addition group and the control group during the composting process of Example 3;

[0035] FIG6 is a comparison chart showing the changes in humic substance HS and humic acid HA content in the 0.5% MnFe2O4 addition group and the control group during the composting process of Example 3. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0037] Preparation method of MnFe2O4 in the embodiment:

[0038] Prepare 0.1 mol L -1Ferric chloride and 0.05 mol L -1 Mixed solution of manganese chloride, add 3 mol L -1 NaOH solution was added to a pH of 12. The suspension was then injected into an autoclave, which was then placed in a muffle furnace for reaction (heating to 250°C at a rate of 10°C / min for 12 hours). After the reaction was complete and the autoclave cooled to room temperature, the sample was removed and washed several times with alternating deionized water and ethanol until the pH of the washings remained stable. Finally, the sample was dried in a vacuum drying oven (60°C for 12 hours) to obtain a dark brown powder. This powder was then ground and passed through a 300-mesh sieve for later use.

[0039] Example 1

[0040] (1) Material Preparation and Mixing: In this example, chicken manure (70% moisture content) was obtained from a chicken farm in Nanjing, and wheat straw (8% moisture content) was obtained from the Liuhe Experimental Field of the Jiangsu Academy of Agricultural Sciences. The wheat straw was crushed to < 3 cm. Fresh chicken manure and wheat straw were mixed in a mass ratio of 5:1, and water was added to adjust the moisture content to 60% and the C / N ratio to 25. MnFe2O4 was added to the compost at 0.01% of the dry weight of the initial compost material along with the water. The group with MnFe2O4 added was designated as the experimental group, and the group without the additive was designated as the control group.

[0041] (2) Aerobic composting: The compost obtained in step (1) was subjected to conventional aerobic composting. In this embodiment, conventional composting was performed using the method disclosed in the reference "Sun HJ, Chen S, Zhu N et al., Hydrothermal carbonization aqueous phase promotes nutrient retention and humic substance formation during aerobic composting of chicken manure. Bioresource Technology, 2023, 385: 129418." A cubic insulated box measuring 63 cm in length, 48 cm in width, and 36 cm in height was used for composting. The compost was turned over every 2-3 days during the temperature rise and high temperature periods, and every 7 days during the temperature drop and mature period. The aerobic composting time was 30 days (both the experimental group and the control group were heated to above 50°C on the first day of composting, maintained above 50°C for 11 days, and then underwent a temperature drop and mature period). After testing, the compost products of the experimental group and the control group met the organic fertilizer maturity standards (Agricultural Industry Standard of the People's Republic of China NY / T525-2021).

[0042] The resistance genes and humification parameters of the two composting processes were tested, and the results are shown in Figures 1a, 1b, 1c, 1d, and 2. Figures 1a-1d show the detection results of the relative abundance of sulfonamide, tetracycline, macrolide, and aminoglycoside resistance genes, respectively. Among them, in the relative abundance detection results of tetracycline resistance genes shown in Figure 1b, the tetC gene content is extremely low, about 10 -5 about.

[0043] Resistance gene determination method: High-throughput qPCR method. The relative abundance of the target gene was normalized to the 16S rRNA gene copy number. The determination method was based on the method disclosed in the literature "Zhu N, Long YJ, Kan ZX et al., Reduction of mobile genetic elements determines the removal of antibiotic resistance genes during pig manure composting after thermal pretreatment. Bioresource Technology, 2023, 387: 129672."

[0044] As shown in Figures 1a-1d, the relative abundances of the four resistance genes decreased over the course of aerobic composting. However, a relatively high number of resistance genes remained in the control group after 30 days of aerobic composting. The addition of 0.01% MnFe₂O₄ significantly promoted the degradation of resistance genes. By the end of composting, the relative abundances of sulfonamide resistance genes decreased by 60%, tetracycline resistance genes by 50%, macrolide resistance genes by 80%, and aminoglycoside resistance genes by 66%.

[0045] Figure 2 (a) and (b) show the results of HS and HA, respectively. HS and HA determination methods: 2 g of ground compost sample was added to 20 mL of extraction solution (0.1 mol / L NaOH and 0.1 mol / L Na₄P₂Oₐ, volume ratio 1:1). The mixture was shaken at room temperature for 2 hours and centrifuged at 4000 rpm for 10 minutes. The supernatant was extracted and the residue was discarded. This process was repeated three times. The filtrate was the total HS. Two-thirds of the HS was acidified with 6 mol / L hydrochloric acid to a pH of 1.0-2.0. The mixture was stirred thoroughly and allowed to stand overnight at room temperature. The precipitate, HA, was dissolved with 0.1 mol / L KOH and the volume was fixed. HS and HA were determined using a TOC analyzer.

[0046] As shown in Figure 2, the degree of humification gradually increased as the aerobic composting process progressed. At the end of the composting period in the control group, humus HS increased by 33% and humic acid HA increased by 89%. The addition of 0.01% MnFe2O4 significantly promoted humification during the composting process. By the end of the composting period, humus HS increased by 14% and humic acid HA increased by 15% compared to the control group.

[0047] Example 2

[0048] (1) Material Preparation and Mixing: In this example, chicken manure (75% moisture content) was obtained from a chicken farm in Zhenjiang City, and wheat straw (7% moisture content) was obtained from a straw farm in Lianyungang. The wheat straw was crushed to 1-3 cm. Fresh chicken manure and wheat straw were mixed in a mass ratio of 3:1, and water was added to adjust the moisture content to 55% and the C / N ratio to 30. MnFe2O4 was added to the compost at 0.1% of the dry weight of the initial compost material along with the water. The compost with MnFe2O4 was designated as the experimental group, and the control group was designated as the control group.

[0049] (2) Aerobic composting: The compost obtained in step (1) was subjected to conventional aerobic composting (the steps are the same as those in Example 1). A cubic insulated box with a length of 63 cm, a width of 48 cm, and a height of 36 cm was used for composting. The compost was turned once every 2-3 days during the temperature rise period and the high temperature period, and once every 7 days during the temperature fall period and the mature period. The aerobic composting time was 30 days (both the experimental group and the control group were heated to above 50°C on the first day of composting, maintained above 50°C for 10 days, and then underwent a cooling and mature period). After testing, the compost products of the experimental group and the control group met the organic fertilizer mature standard (NY / T525-2021).

[0050] Resistance genes and humification parameters were detected during the two composting processes using the same detection method as in Example 1. The results are shown in Figures 3a, 3b, 3c, 3d, and 4. Figures 3a-3d are the detection results of the relative abundance of sulfonamide, tetracycline, macrolide, and aminoglycoside resistance genes, respectively. In the tetracycline resistance gene relative abundance detection results shown in Figure 3b, the tetC gene content is extremely low, approximately 10 -5 about.

[0051] Figures 3a-3d show that the relative abundance of the four resistance genes decreased over the course of aerobic composting, but a relatively high level of resistance genes remained in the control group after 30 days of aerobic composting. The addition of 0.1% MnFe₂O₄ significantly promoted the degradation of resistance genes. By the end of composting, the relative abundance of sulfonamide resistance genes decreased by 71%, tetracycline resistance genes by 56%, macrolide resistance genes by 20%, and aminoglycoside resistance genes by 45%.

[0052] Figure 4 (a) and (b) show the test results for humic substances (HS) and humic acid (HA), respectively. As shown in Figure 4, the degree of humification gradually increased as the aerobic composting process progressed. At the end of the composting period in the control group, humic substances (HS) increased by 33% and humic acid (HA) increased by 91%. The addition of 0.1% MnFe₂O₄ significantly promoted the humification process. At the end of the composting period, humic substances (HS) increased by 12% and humic acid (HA) increased by 9% compared to the control group.

[0053] Example 3

[0054] (1) Material Preparation and Mixing: In this example, chicken manure (60% moisture content) was obtained from a chicken farm in Yancheng City, and wheat straw (9% moisture content) was obtained from a straw farm in Yancheng City. The wheat straw was crushed to 1-3 cm. Fresh chicken manure and wheat straw were mixed in a mass ratio of 6:1, and water was added to adjust the moisture content to 65% and the C / N ratio to 20. MnFe2O4 (0.5% of the dry weight of the initial compost material) was added along with the water. The group with MnFe2O4 added was designated as the experimental group, and the group without the additive was designated as the control group.

[0055] (2) Aerobic composting: The compost obtained in step (1) was subjected to normal aerobic composting (the steps are the same as those in Example 1). A cubic insulated box with a length of 63 cm, a width of 48 cm, and a height of 36 cm was used for composting. The compost was turned once every 2-3 days during the temperature rise period and the high temperature period, and once every 7 days during the temperature fall period and the mature period. The aerobic composting time was 30 days (both the experimental group and the control group were heated to above 50°C on the first day of composting, maintained above 50°C for 8 days, and then underwent a cooling and mature period). After testing, the compost products of the experimental group and the control group met the organic fertilizer mature standard (NY / T525-2021).

[0056] The resistance genes and humification parameters of the two composting processes were detected using the same detection method as in Example 1. The results are shown in Figures 5a, 5b, 5c, 5d, and 6. Figures 5a-5d are the detection results of the relative abundance of sulfonamide, tetracycline, macrolide, and aminoglycoside resistance genes, respectively. Among them, in the relative abundance detection results of tetracycline resistance genes shown in Figure 5b, the tetC gene content is extremely low, about 10 -5 about.

[0057] Figures 5a-5d show that the relative abundance of the four resistance genes decreased over the course of aerobic composting. However, a relatively high level of resistance genes remained in the control group after 30 days of aerobic composting. The addition of 0.5% MnFe₂O₄ significantly promoted the degradation of resistance genes. By the end of composting, the relative abundance of sulfonamide resistance genes decreased by 73%, tetracycline resistance genes by 57%, macrolide resistance genes by 29%, and aminoglycoside resistance genes by 63% compared to the control.

[0058] Figure 6 (a) and (b) show the test results for humic substances (HS) and humic acid (HA), respectively. As shown in Figure 6, the degree of humification gradually increased as the aerobic composting process progressed. At the end of the composting period in the control group, humic substances (HS) increased by 34% and humic acid (HA) increased by 88% compared to the initial level. The addition of 0.5% MnFe₂O₄ significantly promoted the humification process. At the end of the composting period, humic substances (HS) increased by 2% and humic acid (HA) increased by 6% compared to the control group.

[0059] Comparative Example 1

[0060] (1) Material preparation and mixing: In the comparative example, the chicken manure raw material was fresh chicken manure from a chicken farm in Nanjing (moisture content 70%, the same source as in Example 1), and the wheat straw was taken from the Liuhe experimental field of Jiangsu Academy of Agricultural Sciences (moisture content 8%, the same source as in Example 1). The wheat straw was crushed to <3 cm.

[0061] Fresh chicken manure and wheat straw were mixed in a mass ratio of 5:1, and appropriate amount of water was added to adjust the moisture content to 60% and the C / N ratio to 25. 0.01% MnO2 of the dry weight of the initial compost material was added along with the water. The group with added MnO2 (purchased from McLean, China) was set as the experimental group, and the group without additives was set as the control group.

[0062] (2) Aerobic composting: The compost obtained in step (1) was subjected to conventional aerobic composting (the steps are the same as those in Example 1). A cubic insulated box with a length of 63 cm, a width of 48 cm, and a height of 36 cm was used for composting. The compost was turned once every 2-3 days during the temperature rise period and the high temperature period, and once every 7 days during the temperature fall period and the mature period. The aerobic composting time was 30 days (both the experimental group and the control group were heated to above 50°C on the first day of composting, maintained above 50°C for 11 days, and then underwent a cooling and mature period). After testing, the compost products of the experimental group and the control group met the organic fertilizer mature standard (NY / T525-2021).

[0063] The resistance genes and humification parameters of the two groups were tested during the composting process using the same method as in Example 1. The results were compared with those of the MnFe2O4 addition group in Example 1, and are shown in Table 1.

[0064] Table 1 Relative abundance of resistance genes in mature compost products of each treatment group

[0065]

[0066] As shown in Table 1, compared with the control, MnO2 addition increased the relative abundance of various resistance genes in the compost, while reducing the content of humic acid (HS) by 13% and showing a limited increase in humic acid (HA) by 4.7%. However, MnFe2O4 addition significantly promoted the degradation of resistance genes, with the relative abundance of sulfonamide resistance genes in the compost decreasing by 60%, tetracycline resistance genes by 50%, macrolide resistance genes by 80%, and aminoglycoside resistance genes by 66% compared with the control. Furthermore, MnFe2O4 addition significantly promoted the humification of the compost, with humic acid (HS) increasing by 14% and humic acid (HA) by 15% compared with the control.

[0067] Comparative Example 2

[0068] (1) Material preparation and mixing: In this example, the chicken manure raw material was fresh chicken manure from a chicken farm in Nanjing (moisture content 70%, the same source as in Example 1), and the wheat straw was taken from the Liuhe experimental field of Jiangsu Academy of Agricultural Sciences (moisture content 8%, the same source as in Example 1). The wheat straw was crushed to 1-3 cm.

[0069] Fresh chicken manure and wheat straw were mixed in a mass ratio of 5:1, and the carbon-nitrogen ratio was adjusted to 25. An appropriate amount of water was added to adjust the moisture content to 60%. 0.01% MnSO4 of the dry weight of the initial compost material was added along with the water. The group with added MnSO4 (purchased from McLean, China) was set as the experimental group, and the group without additives was set as the control group.

[0070] (2) Aerobic composting: The compost obtained in step (1) was subjected to conventional aerobic composting (the steps are the same as those in Example 1). A cubic insulated box with a length of 63 cm, a width of 48 cm, and a height of 36 cm was used for composting. The compost was turned once every 2-3 days during the temperature rise period and the high temperature period, and once every 7 days during the temperature fall period and the mature period. The aerobic composting time was 30 days (both the experimental group and the control group were heated to above 50°C on the first day of composting, maintained above 50°C for 11 days, and then underwent a cooling and mature period). After testing, the compost products of the experimental group and the control group met the organic fertilizer mature standard (NY / T525-2021).

[0071] The resistance genes and humification parameters of the two groups were tested during the composting process using the same method as in Example 1. The results were compared with those of the MnFe2O4 addition group in Example 1, and are shown in Table 2.

[0072] As shown in Table 2, compared with the control, the addition of MnSO4 actually increased the relative abundance of various resistance genes in the compost. Meanwhile, the humic HS content remained unchanged, while the humic acid HA content increased slightly (by 7%). However, the addition of MnFe2O4 significantly promoted the degradation of resistance genes. The relative abundance of sulfonamide resistance genes in the compost decreased by 60%, tetracycline resistance genes by 50%, macrolide resistance genes by 80%, and aminoglycoside resistance genes by 66%. Furthermore, the addition of MnFe2O4 significantly promoted the humification of the compost, with humic HS content increasing by 14% and humic acid HA content increasing by 15% compared with the control.

[0073] Table 2 Relative abundance of resistance genes in mature compost products of each treatment group

[0074]

[0075] Although the above embodiments have been used to fully describe the present invention through general explanations and specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the present invention. Therefore, such modifications or improvements, which do not depart from the spirit of the present invention, are intended to fall within the scope of protection claimed in the present invention.

Claims

1. A method for removing resistance genes and promoting humification in enhanced aerobic composting, characterized in that: The specific steps are as follows: 1) After mixing livestock and poultry manure and compost auxiliary materials, adjust the moisture content to 55%-65%, and add MnFe2O4 to obtain compost raw materials; The livestock and poultry manure includes one or more of pig manure, chicken manure, sheep manure or cow manure; The composting auxiliary material includes one or more of wheat straw, corn straw, rice straw or sawdust; 2) Aerobic composting is performed using the compost raw materials for 20-30 days to achieve the removal of resistance genes in the enhanced compost product and promote humification.

2. The method for enhancing the removal of resistance genes and promoting humification in aerobic composting according to claim 1, characterized in that: In step 1), the mass ratio of livestock and poultry manure to compost auxiliary material is 3:1-6:

1.

3. The method for enhancing the removal of resistance genes and promoting humification in aerobic composting according to claim 1, characterized in that: Step 1): The length of the composting auxiliary material is less than 3 cm.

4. The method for enhancing the removal of resistance genes and promoting humification in aerobic composting according to claim 1, characterized in that: Step 1) The amount of MnFe2O4 added is 0.01%-0.5% of the dry weight of the compost raw material.

5. The method for enhancing the removal of resistance genes and promoting humification in aerobic composting according to claim 1, characterized in that: Step 2) The aerobic composting means that the compost is turned every 2-3 days during the temperature rise period and the high temperature period, and every 7 days during the temperature drop period and the mature period, and the compost temperature is higher than 50°C for no less than 5 days.

6. The method for enhancing the removal of resistance genes and promoting humification in aerobic composting according to claim 1, characterized in that: Step 2) The resistance gene includes at least one of sulfonamide, tetracycline, macrolide, and aminoglycoside resistance genes.

7. The method for removing resistance genes and promoting humification in enhanced aerobic composting according to any one of claims 1 to 6, characterized in that: Step 1) The MnFe2O4 is prepared by the following method: -1 Ferric chloride and 0.05 mol L -1 To the mixed solution of manganese chloride, 3 mol L -1 The pH was adjusted to 12 by NaOH; the mixture was then placed in a muffle furnace and heated to 250°C at a rate of 10°C / min, reacted for 12 h, and naturally cooled. The solid was washed with deionized water and ethanol, dried, ground, and passed through a 300-mesh sieve to obtain the MnFe2O4.

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